Fluid-expanded piston for oil pumps



April 29, 1930. J. F. MITCHELL FLUID EXPANDED PISTON FOR OIL PUMPS Filed June 11, 1927 inve Mio@ SHO: ne l1 Patented Apr. 29, 1930 UNITED STA TES Pix-.TENT OFFICE JOHN F. MITCHELL, OF COTTON VALLEY, LOUISIANA, ASSIGNOR OF FORTY-FIVE PE v CENT To LEWIS e. WILLIAMS,

OF COTTON kVALLEY, LOUISIANA rLUTD-EXPANDED PIsroN ron OIL rinvrrs` Application led June 11 fluid in the well casing.

A further object is to provide a-pisto`n or plunger of the type indicated,'and in connection therewith a removable valve seat which `may be threaded into the lower end of the plunger, and which includesa tubular scraping device designed to remove from the Wallof an inner element of, the .well casing any sand or other foreign mater1al,-an annular space being afforded between the scraping element and the lower end of the piston, to permit sand or the like, tending to collect here, to pass thru ports toward the center of the combined valve seat and Scraping element,and to pass into the main strea of uid flowing lfrom vthe well.- 'i `With the'foregoing and other objects in view, the invention consists in the novel construction and arrangement of. elements described, illustratedI and claimed, it being understood that,modiiicatiol'is may be made within the scope of the claim without, departing from the spirit of the invention.

- In the drawings forming part of this apl .,plication,

Figure 1 is a view in vertical section, thr the well casing and thru the-tubular piston or Iplunger.'

igure 2 is a similar view, the piston being on the downward stroke, whereas in Figurel the bore of element l5 constituting the inner 'of Figure 1, in thedirection of the arrows.

Figure 5 is a transverse section on line 5-5 .of Figure `1, also in the direction ofthe arrows. l

A section 10 of the'well casin is connected by a sleeve or coupling 11 with t at section of 1927. Serial N0. 198,160.

ner threaded portion 12, and a lower externally threaded portion 13. Portion 13 cooperates with the internally threaded end ofl casing section 14, the latter lreceiving a sleeve 15 in which the piston or plunger operates. 4This arrangement permits of the renew al of element K15,. when required, and this element abuts at its upper end the end 0f portion 13, when the parts are screwed up tightly. ,Afslight space at 16 permits of the necessary longitudinal movement of the elements in order to secure proper connection. The lower end portion 0f sleeve 15 abuts the externally threaded end of the sleeve or coupling 18, and theinternally threaded end of casing section 14 engages a corresponding portion on said sleeve 18, space being pro-v vided if desired at 19, for the purpose previously indicated. f

A lower sleeve or coupling 20 may be provided with a flange 21, and thiselement .'20

is threaded into sleeve 18, and permits of the operates with this seat, and operates within `a cage structure 251 The piston rod 27 has threadedv connection at 28 with the piston which includes a spiderlike structure 29 having the threaded head 29', -tlfe elongated vtubular element constituting the piston per se being shown at 30, and being expansible under Athe weight of the J columnof oil or other Huid in the well casing, so that no packing is required, the outer wall of element 30 coming into contact with portion of that section of the casing in which the piston or plunger operates.

A ball valve 32 cooperates with threaded and removable seat 33, the'latter cooperating with the internally the tubular piston.l

This element 33, the up er end of which constitutes the seat, has ,ormed integrally therewith a lower Aextension 35 constituting a tubular scraping or cleaning device, for the the casing designed to receive the piston or. purpose of removing from the bore of the plunger, said element 11 having an upper incasng section 15 any foreign material which threaded portion 34 0i may tend to collect thereon. The material so removed passes into the main stream of oil flowing from the casing and pumped by the mechanism just described.

An annular space 36 between the scraping element 35 and the end portionv 34, permits of the passage therethru Vof sand or the like, which may tend to flow downwardly in the easing, the material passing thru ports 37, and entering the main stream lof oil, `so that wear, or undue wear 0n the casing section 15 is avoided, by the removal 'of all foreign material, so far as it is possible to effect this result. A slightly reduced diameter may be provided at 34,- to avoid any tendency to bind, due to the generation of heat, the upper p0rtion of the expansible piston beingrsufiiciently flexible to produce a practically fluid-tight Contact, without undue friction. lVhat is claimed ifm-f. In a device of the 'elassvdescribed a well easing,l a piston operating Within said casing and having an upper open and unobstructed \end portion provided with thin expansible walls of uniform thickness, the piston including a tubular extension having a loweropen end acting as a casing cleaning element, the

extension having a reduced portion provid ing an annular chamber at the end of the tubular piston, the extension being provided with )orts extending radially thereof, to provide for the passageof material from the annular chamber to the inner portion of the extension. l

In testimony JOHN F. MITCHELL.`

hereof I aifix my signature. I 

